linux-kernel - RE: [PATCH v9 3/9] watchdog: rzg2l_wdt: Use pm_runtime_resume_and

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Message-ID:
 <TY3PR01MB11346A460DB4209BE98DCF8B486DA2@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Mon, 8 Jul 2024 09:20:10 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Claudiu.Beznea <claudiu.beznea@...on.dev>, "wim@...ux-watchdog.org"
	<wim@...ux-watchdog.org>, "linux@...ck-us.net" <linux@...ck-us.net>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>, "geert+renesas@...der.be"
	<geert+renesas@...der.be>, "magnus.damm@...il.com" <magnus.damm@...il.com>
CC: "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: RE: [PATCH v9 3/9] watchdog: rzg2l_wdt: Use
 pm_runtime_resume_and_get()


> Subject: RE: [PATCH v9 3/9] watchdog: rzg2l_wdt: Use pm_runtime_resume_and_get()
> 
> Hi Claudiu,
> 
> > -----Original Message-----
> > From: Claudiu <claudiu.beznea@...on.dev>
> > Sent: Friday, May 31, 2024 7:57 AM
> > Subject: [PATCH v9 3/9] watchdog: rzg2l_wdt: Use
> > pm_runtime_resume_and_get()
> >
> > From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >
> > pm_runtime_get_sync() may return with error. In case it returns with
> > error
> > dev->power.usage_count needs to be decremented.
> > dev->pm_runtime_resume_and_get()
> > takes care of this. Thus use it.
> >
> > Along with it the rzg2l_wdt_set_timeout() function was updated to
> > propagate the result of
> > rzg2l_wdt_start() to its caller.
> >
> > Fixes: 2cbc5cd0b55f ("watchdog: Add Watchdog Timer driver for RZ/G2L")
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> > Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> > ---
> >
> > Changes in v9:
> > - collected Guenter's Rb tag
> >
> > Changes in v8:
> > - none
> >
> > Changes in v7:
> > - none
> >
> > Changes in v6:
> > - none
> >
> > Changes in v5:
> > - none
> >
> > Changes in v4:
> > - none
> >
> > Changes in v3:
> > - none
> >
> > Changes in v2:
> > - propagate the return code of rzg2l_wdt_start() to it's callers
> >
> >
> >  drivers/watchdog/rzg2l_wdt.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/watchdog/rzg2l_wdt.c
> > b/drivers/watchdog/rzg2l_wdt.c index 1741f98ca67c..d87d4f50180c 100644
> > --- a/drivers/watchdog/rzg2l_wdt.c
> > +++ b/drivers/watchdog/rzg2l_wdt.c
> > @@ -123,8 +123,11 @@ static void rzg2l_wdt_init_timeout(struct
> > watchdog_device *wdev)  static int rzg2l_wdt_start(struct watchdog_device *wdev)  {
> >  	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +	int ret;
> >
> > -	pm_runtime_get_sync(wdev->parent);
> > +	ret = pm_runtime_resume_and_get(wdev->parent);
> > +	if (ret)
> > +		return ret;
> 
> Checking ret will lead to imbalance. It should be ret < 0 as ret = 1 corresponds to RPM_ACTIVE and
> the API does not call put() when ret = 1; see [1] and [2]
> 
> [1] https://elixir.bootlin.com/linux/v6.10-rc6/source/drivers/base/power/runtime.c#L778
> 
> [2] https://elixir.bootlin.com/linux/v6.10-rc6/source/include/linux/pm_runtime.h#L431

Please ignore me. Sorry for the noise.

the code for pm_runtime_resume_and_get() seems to be correct.
https://elixir.bootlin.com/linux/latest/source/include/linux/pm_runtime.h#L436

Cheers,
Biju